Heat sinking devices may be coupled to a heat-generating device, such as a power electronics device, to remove heat and lower the maximum operating temperature of the heat-generating device. Cooling fluid may be used to receive heat generated by the heat-generating device by convective thermal transfer and remove such heat from the heat-generating device. For example, a jet of cooling fluid may be directed such that it impinges a surface of the heat-generating device. Another method may include removing heat from a heat-generating device by passing cooling fluid between and around a finned heat sink made of thermally conductive material, such as aluminum.
However, as power electronic devices are designed to operate at increased power levels and generate increased corresponding heat flux due to the demands of newly developed electrical systems, conventional heat sinks are unable to adequately remove the heat flux to effectively lower the operating temperature of the power electronics to acceptable temperature levels. Additionally, while active liquid cooling architectures, such as single and two-phase jet impingement or microchannel heat sinks can alleviate these thermal demands, these systems require dedicated auxiliary components, for example, compressors/pumps, fluid connects, filters, etc., which may be weak points for overall system reliability.
Vapor chambers may offer a viable solution to dissipating localized hotspots while maintaining an acceptable level of reliability. Vapor chambers may transfer heat from hotspots to porous wick structures having cooling fluid that boils within a sealed vapor chamber. The vapor rises away from the localized hotspot extracting heat with the vapor and condensing over an adjacent porous surface, which through capillary action within interconnected porous structures of the vapor chamber cooling fluid is transferred back to hotspots for further heat extraction through boiling. However, current methods of fabricating the porous wick structures face challenges that affect the wicking process and decrease wick performance, such as subtractive processes, which lead to fused particles in critical regions of the porous wick layers reducing their overall performance. Additionally, interconnected structures for returning cooling fluid to hotspots reduce the area available for boiling of the cooling fluid thus reducing cooling performance.
Accordingly, a need exists for multi-layer wick structures with surface enhancement features and improved methods of fabricating multi-layer porous wick structures with surface enhancement features for improved heat dissipation performance by the multi-layer porous wick structure.